Corrosion arrestor for fire extinguisher



p 5 1967' c. K. HUTHSING, JR 3,339,638

CORROSION ARRESTOR FOR FIRE EXTINGUISHER Filed June 9, 1965 INVENTOR. CHARLES K. H(/7f/J//V6, c/E.

. ATTORNEYS United States Patent 3,339,638 CORROSION ARRESTOR FOR FIRE EXTINGUISHER Charles K. Huthsing, Jr., 1685 Shermer Road, Northbrook, II]. 60062 FiledJuue 9, 1965, Ser. No. 462,505 1 Claim. (Cl. 169-30) ABSTRACT OF THE DISCLOSURE The present invention relates to improvements in corrosion ar restors for use in fire exinguishers for preventing corrosion therein. The present invention represents an improvement over applicants previously issued Patents No.

r 2,563,171, dated Aug. 7, 1951, for Apparatus for Controlling Corrosion in Fire Extinguishers, and No. 3,153,453, dated Oct. 20, 19 64, for Corrosion Arrestor for use in Fire Extinguishers.

In each of the aforementioned patents, the invention was partially concerned with the prevention of corrosion to certain internal parts, such as metal siphon tubes, valve housings, and the like, forming a part of the interior construction of the extinguisher.

The present invention is directed for the most part towards preventing corrosion on the inner surface of stainless steel fire extinguisher tanks, as such.

Corrosion of stainless steel tanks of fire extinguishers is most often prevalent under conditions in which water is used as an extinguishing agent, and wherein sodium chloride or salt is contained in the water which reacts to form a solution with other than neutral pH readings. Thus, the present invention is directed, for the most part, to water type extinguishers in which the water with the presence of sodium chloride or other impurities may give rise to acidic or alkaline conditions such that an electrolyte is formed which in turn effects corrosion of the interior of the stainless steel fire extinguishers shell or tank.

Although the invention will be described from the standpoint of pressurized water type extinguishers, it will also be appreciated that the corrosion arrestor of the present invention may also 'be used with soda-acid and foam type extinguishers.

In the aforementioned patents of applicant, magnesium was used as the corrosion arrestor element because of its point in the electromotive series or electro-chemical scale. Thus, since magnesium is at the higher end of the electrochemical scale, it would tend to become a sacrificial anode; further than this, magnesium combines with the water and/or acid to form magnesium hydroxide which also has a neutralizing effect with respect to certain acids that might otherwise corrode the internal components within the fire extinguisher tank or shell.

Since the present invention is, however, directed for the most part, to the extinguisher shell or tank, as such, and since zinc is considerably further up the elect-romotive scale than any of the metals'contained in steel, the corrosion arrestor of the present invention is preferably formed of zinc in view of the lesser expense involved, although it is, of course, possible to use any element higher in the electro-chemical scale.

With this state of the art in mind, one of the objects of the present invention is to provide an improved corrosion arrestor which may be inexpensively formed and securely mounted within the fire extinguisher tank.

Another object of the present invention is to provide an improved corrosion arrestor structure which is so constructed that it will not readilly deteriorate into small pieces or result in any loose particles which could interrupt the discharge of the extinguisher.

A still further object of the present invention is to provide a very simple structure for a corrosion arrestor and for the manufacture of same with the end in view of mass production of the corrosion arrestor as well as avoiding any maintenance therefor.

Still a further object of the present invention is to provide an improved corrosion arrest-or which embodies a sacrificial anode which may be replaced after it has been used up or substantially used up in an electrolytic solution.

These and other objects and advantages of the present invention are generally achieved by providing an improved corrosion arrestor including a U-shaped bracket designed for attachment to the tank sidewall, .a flat member of zinc material functioning as the sacrificial anode metal, and a means of coupling the flat material to the U-shaped bracket.

Several embodiments of the present invention are shown in the drawings, illustrating merely certain forms the invention might take, and in which:

FIGURE 1 is a view of a permanent type corrosion arrestor structure, according to the present invention;

FIGURE 2 is .a view taken in the direction of the arrows 22 of FIGURE 1 illustrating the zinc strip forming the sacrificial material of the corrosion arrestor of FIGURE 1;

, FIGURE 3 is a view of a corrosion arrestor structure in which a replaceable anode disc is embodied; and,

FIGURE 4 is a view of a modified form of the corrosion arrestor structure of FIGURE 3 showing a somewhat different mounting bracket and position of same with respect to the fire extinguisher tank.

Referring now to the drawings, there is shown in FIG- URES l and 2, a corrosion arrestor 10 mounted on the bottom portion 11 of an extinguisher tank 12. The bottom portion 11 is usually formed separately, at which time the corrosion arrestor 10 is mounted therein; thereafter, the bottom portion 11 is welded to the sidewalls 12 of the tank.

The corrosion arrestor 10 embodies an elongated strip 13 which is bent at its ends to form legs 14, the latter being in turn bent to form feet 15 for spot welding to the tank bottom 11.

The actual sacrificial metal or anode is formed by a zinc strip 16 which is secured to the elongated member 13 of the bracket 10 by rivets 17. Thus, a permanent type corrosion arrestor is formed with the strip 16 forming the sacrificial metal preventing corrosion of the interior of the sidewalls of the tank 12, the latter being formed of stainless steel. Usually the corrosion arrestor will be employed in tanks including plastic siphon tubes not shown in the attached drawing.

Under certain operating conditions, the structure for a corrison arrestor illustrated in FIGURE 1 may not be quite so advantageous. Other than the fact that the corrosion arrestor is of a permanent type, there also exists a possibility that the zinc strip may be eaten away intermediate of the ends such that portions of the stri may become free within the fire extinguisher tank with the resultant possibility of interference with the discharge of the extinguisher.

In order to avoid the latter possibility and at the same time provide for replacement of the sacrificial zinc maperhaps be preferable.

The embodiment of FIGURE 3 discloses a replaceable corrosion arrestor unit also located in the bottom portion of the extinguisher. Thus, looking at FIGURE 3, the same parts have been designated by the same numerals, such that the corrosion arrestor 18 is secured to the bottom 11 of the extinguisher tank 12. The corrosion arrestor 18 includes a U-shaped bracket 19 having feet 20 welded to the bottom 11 of the fire extinguisher tank. The U-shaped bracket 19 further embodies an upper base portion 21 preferably having welded to the bottom thereof a nut 22 designed to receive a screw 23.

Positioned above the base portion 21 of the bracket 18 is a circular disc 24 of Zinc material functioning as the sacrificial anode in this case.

With this type of structure, it will be appreciated that the likelihood of any portion of the circular disc 24 being eaten away so as to form free material within the extinguisher tank is extremely remote. In other words, it is much more likely with this type of structure that the entire disc will be eaten away gradually and in a radially inward direction. Also, it will be appreciated that a new disc may be used to replace the one that is disposed of by merely Undoing the screw 23, inserting a new disc, and thereafter rethreading the screw 23 in the nut 22 welded to the portion 21 of the bracket 19.

Some difliculty, however, might be encountered in obtaining access to the screw 23 through the upper opening in the extinguisher; for this reason, an alternate construction is shown in FIGURE 4.

Referring now to FIGURE 4, in which the same numerals indicate the same parts, there is shown a bracket 25 also U-shaped, including a foot 26 welded to the extinguishers sidewalls 12 and another foot 27 designed to have welded thereto a nut 28 for receiving a screw 29. The foot 27 has coupled thereto a disc of sacrificial zinc material 30 in the same manner as the construction of FIGURE 3.

In this construction, it will be appreciatedin view of the proximity of the corrosion arrestor to the top opening of the extinguisherthat access may be had thereto more conveniently for unthreading of the screw and reinsertion of a new disc 30. In this respect, it is only necessary, for proper functioning, that the corrosion arrestor be below the fill line of the extinguisher.

From the foregoing, it will be appreciated that certain variations and modifications may be made to the improved corrosion arrestor of the present invention Without departing from the spirit and scope of the invention as set forth in the following claim.

What is claimed is:

In a fire extinguisher designed to receive a liquid extinguisher agent and having a stainless steel shell including an upper opening, a corrosion arrestor designed for mounting in said shell, said corrosion arrestor comprising: a bracket having one portion securely connected to the interior sidewall of said stainless steel shell proximate said upper opening so that access may be had through said opening, another portion of said bracket being designed to receive a screw; a substantially flat member made of metal higher in the electrochemical scale than stainless steel connected'at a central portion to said another portion of said bracket by said screw and in contact therewith such that said flat member is in metal to metal contact with said bracket whereby said flat member acts as a sacrificial anode relative to said stainless steel shell so that the flat member is eaten away generally in a direction from its periphery towards its central portion receiving said screw as a result of any electrolytical action from said liquid rather than the stainless steel shell and whereby said fiat member may be replaced by removing said screw when eaten away as a sacrificial anode.

References Cited UNITED STATES PATENTS 8/1951 Huthsing 169-33 10/1964 Huthsing 169-30 

